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With the Macondo well's oil leak finally stopped using a procedure called a static kill, here’s a review of what BP tried during the nearly three months the oil gushed into the Gulf of Mexico.
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A 100-ton box lowered over the gushing oil failed because ice crystals called methane hydrates formed from natural gas flowing from the well and clogged the box’s plumbing. A much smaller containment device BP called a top hat was lowered to the ocean floor, but never usedl.
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A six-inch tube inserted into the broken riser pipe that once connected the well to the drilling rig above collected about 1,000 barrels of oil a day and sent it to a tanker on the surface.
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An attempt to stop the well by pumping mud, cement and chunks of rubber into its damaged blowout preventer failed because the material couldn’t overcome the pressure of the gushing oil and gas.
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A pipe attached after remote control robots cut the damaged riser sent 15,000 barrels a day to a tanker.
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The plumbing used in the unsuccessful top kill was reversed, capturing up to 10,000 barrels of oil a day and sending it to the multipurpose vessel Q4000, which flared off the oil but couldn’t store it.
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A 75-ton stack of valves attached to the Macondo’s blowout preventer using a specially made metal coupling system stopped the flow of oil, but was not viewed as a permanent fix.
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Once the capping stack stabilized well pressure, an approach similar to the top kill sealed the well when engineers forced oil back into the reservoir with drilling mud, then plugged it from the top with cement.
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A well started days after the April 20 blowout intercepted the Macondo at its source. It will provide further protection against oil flow by cementing the well from the bottom.
